A bridge is in the form of a parabolic archway. The bridge's height (y) with respect to the horizontal distance (x) can be modeled by the quadratic function y = -0.04x2 +0.4x.
Enter the maximum height of the bridge. All measurements are in feet.

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth